American Maryland Imam, Suleiman Anwar Bengharasa gave a lecture in 2010. This lecture was given to a small group of advanced students at the Abu Huraira Center in 2010. Below in an excerpt.
There are some Muslims amongst us these days who want to go around and say: “Oh! Islam was never spread by the sword.” That’s a blatant lie. It was spread many times by the sword. The implementation of the Sharia was spread by the sword.
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Undoubtedly taking the initiative in fighting has a great effect in spreading Islam and bringing people into the religion of Allaah in crowds. Hence the hearts of the enemies of Islam are filled with fear of jihad.
“And We brought forth iron wherein is mighty power (in matters of war), as well as many benefits for mankind, that Allaah may test who it is that will help Him (His religion) and His Messengers in the unseen”
So whoever deviates from the Book is to be brought back with iron, i.e. by force. Hence the soundness of the religion is based on the Qur’aan and the Sword. It was narrated that Jaabir ibn ‘Abd-Allaah (may Allaah be pleased with him) said: The Messenger of Allaah (peace and blessings of Allaah be upon him) commanded us to strike with this, meaning the sword, whoever turns away from this, meaning the Qur’aan.